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linux-stable/drivers/cpufreq/Kconfig
David Dai 4fd06a5358 cpufreq: add virtual-cpufreq driver 
Introduce a virtualized cpufreq driver for guest kernels to improve
performance and power of workloads within VMs.

This driver does two main things:

1. Sends the frequency of vCPUs as a hint to the host. The host uses the
hint to schedule the vCPU threads and decide physical CPU frequency.

2. If a VM does not support a virtualized FIE(like AMUs), it queries the
host CPU frequency by reading a MMIO region of a virtual cpufreq device
to update the guest's frequency scaling factor periodically. This enables
accurate Per-Entity Load Tracking for tasks running in the guest.

Co-developed-by: Saravana Kannan <saravanak@google.com>
Signed-off-by: Saravana Kannan <saravanak@google.com>
Signed-off-by: David Dai <davidai@google.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
2024-10-29 12:05:14 +05:30

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# SPDX-License-Identifier: GPL-2.0-only
menu "CPU Frequency scaling"
config CPU_FREQ
bool "CPU Frequency scaling"
help
CPU Frequency scaling allows you to change the clock speed of
CPUs on the fly. This is a nice method to save power, because
the lower the CPU clock speed, the less power the CPU consumes.
Note that this driver doesn't automatically change the CPU
clock speed, you need to either enable a dynamic cpufreq governor
(see below) after boot, or use a userspace tool.
For details, take a look at
<file:Documentation/admin-guide/pm/cpufreq.rst>.
If in doubt, say N.
if CPU_FREQ
config CPU_FREQ_GOV_ATTR_SET
bool
config CPU_FREQ_GOV_COMMON
select CPU_FREQ_GOV_ATTR_SET
select IRQ_WORK
bool
config CPU_FREQ_STAT
bool "CPU frequency transition statistics"
help
Export CPU frequency statistics information through sysfs.
If in doubt, say N.
choice
prompt "Default CPUFreq governor"
default CPU_FREQ_DEFAULT_GOV_USERSPACE if ARM_SA1110_CPUFREQ
default CPU_FREQ_DEFAULT_GOV_SCHEDUTIL if ARM64 || ARM
default CPU_FREQ_DEFAULT_GOV_SCHEDUTIL if (X86_INTEL_PSTATE || X86_AMD_PSTATE) && SMP
default CPU_FREQ_DEFAULT_GOV_PERFORMANCE
help
This option sets which CPUFreq governor shall be loaded at
startup. If in doubt, use the default setting.
config CPU_FREQ_DEFAULT_GOV_PERFORMANCE
bool "performance"
select CPU_FREQ_GOV_PERFORMANCE
help
Use the CPUFreq governor 'performance' as default. This sets
the frequency statically to the highest frequency supported by
the CPU.
config CPU_FREQ_DEFAULT_GOV_POWERSAVE
bool "powersave"
select CPU_FREQ_GOV_POWERSAVE
help
Use the CPUFreq governor 'powersave' as default. This sets
the frequency statically to the lowest frequency supported by
the CPU.
config CPU_FREQ_DEFAULT_GOV_USERSPACE
bool "userspace"
select CPU_FREQ_GOV_USERSPACE
help
Use the CPUFreq governor 'userspace' as default. This allows
you to set the CPU frequency manually or when a userspace
program shall be able to set the CPU dynamically without having
to enable the userspace governor manually.
config CPU_FREQ_DEFAULT_GOV_ONDEMAND
bool "ondemand"
depends on !(X86_INTEL_PSTATE && SMP)
select CPU_FREQ_GOV_ONDEMAND
select CPU_FREQ_GOV_PERFORMANCE
help
Use the CPUFreq governor 'ondemand' as default. This allows
you to get a full dynamic frequency capable system by simply
loading your cpufreq low-level hardware driver.
Be aware that not all cpufreq drivers support the ondemand
governor. If unsure have a look at the help section of the
driver. Fallback governor will be the performance governor.
config CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
bool "conservative"
depends on !(X86_INTEL_PSTATE && SMP)
select CPU_FREQ_GOV_CONSERVATIVE
select CPU_FREQ_GOV_PERFORMANCE
help
Use the CPUFreq governor 'conservative' as default. This allows
you to get a full dynamic frequency capable system by simply
loading your cpufreq low-level hardware driver.
Be aware that not all cpufreq drivers support the conservative
governor. If unsure have a look at the help section of the
driver. Fallback governor will be the performance governor.
config CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
bool "schedutil"
depends on SMP
select CPU_FREQ_GOV_SCHEDUTIL
select CPU_FREQ_GOV_PERFORMANCE
help
Use the 'schedutil' CPUFreq governor by default. If unsure,
have a look at the help section of that governor. The fallback
governor will be 'performance'.
endchoice
config CPU_FREQ_GOV_PERFORMANCE
tristate "'performance' governor"
help
This cpufreq governor sets the frequency statically to the
highest available CPU frequency.
To compile this driver as a module, choose M here: the
module will be called cpufreq_performance.
If in doubt, say Y.
config CPU_FREQ_GOV_POWERSAVE
tristate "'powersave' governor"
help
This cpufreq governor sets the frequency statically to the
lowest available CPU frequency.
To compile this driver as a module, choose M here: the
module will be called cpufreq_powersave.
If in doubt, say Y.
config CPU_FREQ_GOV_USERSPACE
tristate "'userspace' governor for userspace frequency scaling"
help
Enable this cpufreq governor when you either want to set the
CPU frequency manually or when a userspace program shall
be able to set the CPU dynamically, like on LART
<http://www.lartmaker.nl/>.
To compile this driver as a module, choose M here: the
module will be called cpufreq_userspace.
If in doubt, say Y.
config CPU_FREQ_GOV_ONDEMAND
tristate "'ondemand' cpufreq policy governor"
select CPU_FREQ_GOV_COMMON
help
'ondemand' - This driver adds a dynamic cpufreq policy governor.
The governor does a periodic polling and
changes frequency based on the CPU utilization.
The support for this governor depends on CPU capability to
do fast frequency switching (i.e, very low latency frequency
transitions).
To compile this driver as a module, choose M here: the
module will be called cpufreq_ondemand.
For details, take a look at
<file:Documentation/admin-guide/pm/cpufreq.rst>.
If in doubt, say N.
config CPU_FREQ_GOV_CONSERVATIVE
tristate "'conservative' cpufreq governor"
depends on CPU_FREQ
select CPU_FREQ_GOV_COMMON
help
'conservative' - this driver is rather similar to the 'ondemand'
governor both in its source code and its purpose, the difference is
its optimisation for better suitability in a battery powered
environment. The frequency is gracefully increased and decreased
rather than jumping to 100% when speed is required.
If you have a desktop machine then you should really be considering
the 'ondemand' governor instead, however if you are using a laptop,
PDA or even an AMD64 based computer (due to the unacceptable
step-by-step latency issues between the minimum and maximum frequency
transitions in the CPU) you will probably want to use this governor.
To compile this driver as a module, choose M here: the
module will be called cpufreq_conservative.
For details, take a look at
<file:Documentation/admin-guide/pm/cpufreq.rst>.
If in doubt, say N.
config CPU_FREQ_GOV_SCHEDUTIL
bool "'schedutil' cpufreq policy governor"
depends on CPU_FREQ && SMP
select CPU_FREQ_GOV_ATTR_SET
select IRQ_WORK
help
This governor makes decisions based on the utilization data provided
by the scheduler. It sets the CPU frequency to be proportional to
the utilization/capacity ratio coming from the scheduler. If the
utilization is frequency-invariant, the new frequency is also
proportional to the maximum available frequency. If that is not the
case, it is proportional to the current frequency of the CPU. The
frequency tipping point is at utilization/capacity equal to 80% in
both cases.
If in doubt, say N.
comment "CPU frequency scaling drivers"
config CPUFREQ_DT
tristate "Generic DT based cpufreq driver"
depends on HAVE_CLK && OF
select CPUFREQ_DT_PLATDEV
select PM_OPP
help
This adds a generic DT based cpufreq driver for frequency management.
It supports both uniprocessor (UP) and symmetric multiprocessor (SMP)
systems.
If in doubt, say N.
config CPUFREQ_VIRT
tristate "Virtual cpufreq driver"
depends on GENERIC_ARCH_TOPOLOGY
help
This adds a virtualized cpufreq driver for guest kernels that
read/writes to a MMIO region for a virtualized cpufreq device to
communicate with the host. It sends performance requests to the host
which gets used as a hint to schedule vCPU threads and select CPU
frequency. If a VM does not support a virtualized FIE such as AMUs,
it updates the frequency scaling factor by polling host CPU frequency
to enable accurate Per-Entity Load Tracking for tasks running in the guest.
If in doubt, say N.
config CPUFREQ_DT_PLATDEV
tristate "Generic DT based cpufreq platdev driver"
depends on OF
help
This adds a generic DT based cpufreq platdev driver for frequency
management. This creates a 'cpufreq-dt' platform device, on the
supported platforms.
If in doubt, say N.
if X86
source "drivers/cpufreq/Kconfig.x86"
endif
source "drivers/cpufreq/Kconfig.arm"
if PPC32 || PPC64
source "drivers/cpufreq/Kconfig.powerpc"
endif
if MIPS
config BMIPS_CPUFREQ
tristate "BMIPS CPUfreq Driver"
help
This option adds a CPUfreq driver for BMIPS processors with
support for configurable CPU frequency.
For now, BMIPS5 chips are supported (such as the Broadcom 7425).
If in doubt, say N.
config LOONGSON2_CPUFREQ
tristate "Loongson2 CPUFreq Driver"
depends on LEMOTE_MACH2F
help
This option adds a CPUFreq driver for loongson processors which
support software configurable cpu frequency.
Loongson2F and its successors support this feature.
If in doubt, say N.
endif
if LOONGARCH
config LOONGSON3_CPUFREQ
tristate "Loongson3 CPUFreq Driver"
help
This option adds a CPUFreq driver for Loongson processors which
support software configurable cpu frequency.
Loongson-3 family processors support this feature.
If in doubt, say N.
endif
if SPARC64
config SPARC_US3_CPUFREQ
tristate "UltraSPARC-III CPU Frequency driver"
help
This adds the CPUFreq driver for UltraSPARC-III processors.
If in doubt, say N.
config SPARC_US2E_CPUFREQ
tristate "UltraSPARC-IIe CPU Frequency driver"
help
This adds the CPUFreq driver for UltraSPARC-IIe processors.
If in doubt, say N.
endif
if SUPERH
config SH_CPU_FREQ
tristate "SuperH CPU Frequency driver"
help
This adds the cpufreq driver for SuperH. Any CPU that supports
clock rate rounding through the clock framework can use this
driver. While it will make the kernel slightly larger, this is
harmless for CPUs that don't support rate rounding. The driver
will also generate a notice in the boot log before disabling
itself if the CPU in question is not capable of rate rounding.
If unsure, say N.
endif
config QORIQ_CPUFREQ
tristate "CPU frequency scaling driver for Freescale QorIQ SoCs"
depends on OF && COMMON_CLK
depends on PPC_E500MC || SOC_LS1021A || ARCH_LAYERSCAPE || COMPILE_TEST
select CLK_QORIQ
help
This adds the CPUFreq driver support for Freescale QorIQ SoCs
which are capable of changing the CPU's frequency dynamically.
endif
config ACPI_CPPC_CPUFREQ
tristate "CPUFreq driver based on the ACPI CPPC spec"
depends on ACPI_PROCESSOR
depends on ARM || ARM64 || RISCV
select ACPI_CPPC_LIB
help
This adds a CPUFreq driver which uses CPPC methods
as described in the ACPIv5.1 spec. CPPC stands for
Collaborative Processor Performance Controls. It
is based on an abstract continuous scale of CPU
performance values which allows the remote power
processor to flexibly optimize for power and
performance. CPPC relies on power management firmware
support for its operation.
If in doubt, say N.
config ACPI_CPPC_CPUFREQ_FIE
bool "Frequency Invariance support for CPPC cpufreq driver"
depends on ACPI_CPPC_CPUFREQ && GENERIC_ARCH_TOPOLOGY
depends on ARM || ARM64 || RISCV
default y
help
This extends frequency invariance support in the CPPC cpufreq driver,
by using CPPC delivered and reference performance counters.
If in doubt, say N.
endmenu
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